When you put money into a pot, you can win by showing down the best hand, or by having everyone else fold before showdown. You lose money when you put money into a pot and either show down a worse hand than the winner, or fold before showdown.
If your showdown line is breakeven, you're breaking even when you showdown.
If your showdown line is breakeven but your non-showdown line is good, then your style of play is more oriented to folding everyone else out before getting to showdown.
If your overall line is positive, then life is good whether you're deriving profits primarily from sd or from non-sd.
There are too many variables to say that a breakeven sd line is a bad sign (it'd be unusual, though, to see a winning microstakes player with a breakeven sd line I think), though it probably means you're not folding enough (i.e., you're probably a bit of a calling station). There's a stat called WTSD (went to showdown), if it's significantly above 20% you may want to look at your hand histories that you lost at sd and see if you can find a fold before you get to sd.
You may want to try posting your stats in the microgrinder thread and asking for feedback.